With out kitchen remodel we are needing to reroute 2 of our cold air returns. One is at the bottom and the other is at the top of that same wall (one directly above the other 10' ceiling).

Questions.

1. If they are using the same run between studs how much air can the upper one ever really draw since most of the suction would be from the lower one (least resistance)?

2. Is there any problem converting one of the vents to an under kitchen cabinet location and making a qua si vent.

3. I can't find out how to calculate the amount of square inches needed for proper venting using house size, sytle, and BTU's of furnace or airconditioning. Does anyone have an easy formula to get a close estimate or at least a hard formula to use?

4. From what we have noticed it does look like it is code that electrical can not be between the same studs as the cold air return, is that correct?

5. We would be removing the only close to the ceiling vent we currently have. Was this one perhaps put in strictly for the air conditioning, or does it help when using the furnace? We use an evaporative cooler in the summer, so air conditioning concerns are a very minor issue. Will we need to install a higher up cold air return somewhere else in the house?